This invention relates in general to a device for the cumulative digital counting of mechanical events. There is an extensive development of prior art in this general field. More particularly, however, this invention relates to such a device comprising a miniaturized mechanically actuated magnet or magnetocrystalline counter device suitable for particular specialized applications such as the remote reading of utility meters and the like.
Registers for digital data using magnetic domain movable along a wire have been known as illustrated by U.S. Pat. No. 3,447,144 to R. L. Snyder. This type of shift register has been adapted to the remote reading of utility meters as shown in U.S. Pat. No. 3,503,044 to T. I. Bonyhard et al. These devices, however, are electronically driven, do not directly sense mechanical motion, but require relatively complex circuitry for this purpose even to achieve minimally acceptable signal to noise ratios.
Shift registers utilizing magnetic domains movable in the two dimensional plane of a sheet rather than along a wire are illustrated, for example, in U.S. Pat. Nos. 3,540,019 and 3,540,021 both issued to A. H. Bobeck et al. These shift registers also are electronically driven for general purpose applications such as telephone switch boards. A magnetic domain computational arrangement is shown in U.S. Pat. No. 3,845,478 to W. J. Carr. In the latter device domains are propagated at velocities proportional to the product of the magnitudes of two drive control fields responsive to two input signals. This device, also, is then primarily an electronically driven analog computing circuit rather than a mechanically driven digital counting circuit.
Biasing apparatus suitable for use in one type of magnetocrystalline counter disclosed herein has been disclosed and claimed in my own previously issued U.S. Pat. No. 3,831,156 which also contained a discussion of the general properties of movable cylindrical magnetic domains for bubbles which may be formed in uniaxially anistropic magnetic media such as single crystal epitaxial garnet or monolithic orthoferrite platelets. Both my own earlier devices and those of other workers in the prior art have, however, required input data signals to be in the form of electronic pulses.
For many counting applications it is preferred to have an accumulating digital counter which can be directly driven by the occurrence of a mechanical event rather than by electronic pulses. The generation of such pulses may or may not be representative of the counted events, is subject to errors and assuredly requires standby power which is a particular disadvantage in remote or unattended counting applications.